Healthy pregnancy (16)
- Childbirth education: Get ready for labor and delivery
- Pregnancy nutrition: Foods to avoid during pregnancy
- Pregnancy weight gain: What's healthy?
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First trimester (6)
- Fetal development: The first trimester
- First trimester pregnancy: What to expect
- Prenatal care: What to expect during the first trimester
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Second trimester (7)
- Second trimester pregnancy: What to expect
- Prenatal care: What to expect during the second trimester
- Fetal development: The second trimester
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Third trimester (9)
- Overdue pregnancy: What to do when baby's overdue
- Fetal development: The third trimester
- Third trimester pregnancy: What to expect
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Pregnancy problems (14)
- Pregnancy and diabetes: From conception to birth
- Antidepressants: Are they safe during pregnancy?
- Coping with pregnancy loss
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Fetal development: The second trimester
Week 20: The halfway point
Halfway into your pregnancy, or 18 weeks after conception, your baby's delicate skin is protected with a greasy, cheese-like coating called vernix caseosa.
You may be able to feel your baby's first movements, also known as quickening.
By now your baby may be about 6 1/3 inches (160 millimeters) long from crown to rump and weigh more than 11 ounces (320 grams).
Week 21: Baby can swallow
Twenty-one weeks into your pregnancy, or 19 weeks after conception, your baby is about to gain more weight. By this week your baby is becoming more active and can swallow.
Week 22: Baby's hair becomes visible
Twenty-two weeks into your pregnancy, or 20 weeks after conception, your baby is completely covered with a fine, down-like hair called lanugo. The lanugo helps hold the vernix caseosa on the skin. Your baby's eyebrows may be visible.
By now your baby may be 7 1/2 inches (190 millimeters) long from crown to rump and weigh 1 pound (460 grams).
Week 23: Fingerprints and footprints form
Twenty-three weeks into your pregnancy, or 21 weeks after conception, your baby's skin is wrinkled, more translucent than before and pink to red in color.
This week your baby begins to have rapid eye movements. Your baby's tongue will soon develop taste buds. Fingerprints and footprints are forming. For boys, the testes are beginning to descend from the abdomen. For girls, the uterus and ovaries are in place — complete with a lifetime supply of eggs.
Week 24: Real hair grows
Twenty-four weeks into your pregnancy, or 22 weeks after conception, your baby is regularly sleeping and waking. Real hair is beginning to grow on his or her head.
By now your baby may be slightly longer than 8 inches (210 millimeters) from crown to rump and weigh more than 1 1/3 pounds (630 grams).
With intensive medical care, some babies born this week may be able to survive.
Week 25: Exploration continues
Twenty-five weeks into your pregnancy, or 23 weeks after conception, your baby's hands are fully developed — although the nerve connections to the hands have a long way to go. Exploring the structures inside your uterus may become baby's prime entertainment.
Week 26: Baby's fingernails develop
Twenty-six weeks into your pregnancy, or 24 weeks after conception, your baby has fingernails.
Your baby's lungs are beginning to produce surfactant, the substance that allows the air sacs in the lungs to inflate — and keeps them from collapsing and sticking together when they deflate.
By now your baby may be 9 inches (230 millimeters) long from crown to rump and weigh nearly 2 pounds (820 grams).
Week 27: Second trimester ends
This week marks the end of the second trimester. At 27 weeks, or 25 weeks after conception, your baby's lungs, liver and immune system are continuing to mature — and he or she has been growing like a weed. Your baby's crown-to-rump length may have tripled since the 12-week mark.
Previous page(2 of 2)
- Healthy pregnancy: Stages of pregnancy. U.S. Department of Health and Human Services. http://www.4women.gov/pregnancy/you-are-pregnant/stages-of-pregnancy.cfm#second. Accessed March 20, 2009.
- Moore KL, et al. The Developing Human: Clinically Oriented Embryology. 8th ed. Philadelphia, Pa.: Saunders Elsevier; 2003:4.
- Harms RW (expert opinion). Mayo Clinic, Rochester, Minn. May 28, 2009.
